Sean O Neil suggested that i use an exposure function like 1 - exp(-cst * color) in order to fix these colors. I tested it, and i must say, the results are much better now! I had tried a lot of tricks but most of them changed the relative brightness or the colors, or desaturated them too much..
I'm now starting to generate the textures for the terrain, but i'm getting some ugly artifacts and seams. Hopefully i can fix them, and post more screenies..
I bought F.E.A.R this morning. Haven't tried it yet, but i think i'm not going to be very productive this week end.